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Manual for emergency opening of locks (Impression technique (indentation))

Пособие по аварийному открыванию замков (Импрессионная техника (вдавливания))

Indentation Technique - Possession of this hacking method may indicate a professional cracker. Long and painstaking work associated with the gradual filing by file of extra areas of the metal key, part of which is responsible for secrets, this happens until the key becomes a copy of the native.

The undoubted advantages include the fact that you still have a fully working duplicate, with which you can easily open the lock the next time. The master keys do not give such an effect.

This text is a translation of the English version of the manual published on the network. (translation by Alexey Goncharenko,


Knowing and applying the indentation method is invaluable for emergency door lock services. In contrast to the disassembling / breaking method, this indentation method provides not only the opening of the lock, but also the production of the corresponding key. This means that the indentation method (key selection) is not only effective, but also very economical. These working materials on the indentation technology are divided into three main groups:

  • Locks with disk holding devices (levers)
  • Locks with pin retention devices
  • Locks with cylinder and crossbar

All together forms the basis of a theory of technology called IMPRESSION TECHNIQUE (Indentation Technique).

Table of contents

  • Introduction
  • Indentation Basics
  • Markings / prints
  • Key blank preparation
  • Spin and Pinch
  • Types of keys
  • Locks with cylinder - crossbar
  • Concluding observations

1 Fundamentals of the indentation technique

The theoretical side of technology.

First, the key blank is prepared for work.


  • File surface treatment
  • File processing sites
  • Edging

  • A - file processing of one edging (angle 45 °)
  • B - double edging file (with opposite angles of 45 °)
  • C - Blacking / dyeing

Each of these methods is described in detail in the chapter on the manufacture of key blanks.

Fingerprinting procedure.

1. The key blank made for the indentation method is inserted into the channel of the locking cylinder. You must ensure that the disc is inserted into the cylinder as far as possible. In this case, you should not exert too much effort.

2. Firmly clamp the key with special tongs. Then you should very firmly clamp the head of the key inserted into the cylinder with forceps. For this, it is best to use special forceps. These forceps have soft lips, so scratches cannot form on the disc. It should then be ensured that the tongs of the tongs are parallel to each other, since only in this case the greatest force is provided to hold the key blanks.

3.Now, turn the key inserted into the cylinder to the right until it stops. In this case, you should pay attention not to apply too much force, since you can break or bend the blank.

4. In conclusion, a disc clamped by forceps should be pressed several times up or, respectively, down. Because only thanks to such movements noticeable prints appear on the disc.

5. During the next working cycle, turn the key inserted into the cylinder to the left to the stop. At the same time, care should be taken not to apply too much force, since you can break or bend the blank.

6. Now you can remove the blank from the cylinder.

Your blank should during all working processes, that is, from the preparation of the blank to the subsequent manufacture of the key, remain clamped in the tongs. Only in this way it is possible to ensure a sense of permanence of unity in the combination of “blank and tongs” and to avoid mistakes due to uneven clamping of the blank.

The result of the manipulations will lead to the fact that the cylinder pins left obvious signs of markings or prints on the disc.

Now the question is, why do fingerprints appear?

When inserting the blanks, the cylinder pins are extruded to various heights. If the blank is turned all the way, then it should be assumed that no cylinder is manufactured without manufacturing tolerances or cannot be made. One of these tolerances is drilling tolerance; that is, the drills for the pins with their centers are not strictly on the same line, but are slightly offset from the midline. It follows that the pins are locked at different times. Due to this, markings or prints appear either when rotating to the right or left to the stop.

When turning the blanks in the cylinder all the way, the internal pins, which are located in the zone of the separation gap, are blocked in their position.

The contact between the pins of the core and the body is created when the blank moves up and down. Markings and prints occur when moving up and down, and not due to the rotation of the blanks, as is often assumed.

In places where markings and prints are visible, further processing is performed by a file.

The above-mentioned processes for obtaining markings and fingerprints are repeated until the cuts formed during file processing at appropriate places reach the appropriate depth at which the core pins can be removed from the separation gap zone. In this case, the contact force between the pins of the housing and the core will not be sufficient to leave distinct markings or prints on the key.

The main rule of the impression technique is: No file processing in areas where clear markings or prints are not visible!

When performing file processing, only a little material should always be removed, i.e. irregularly no more than 0.5 mm. Naturally, in this case the key is produced a little slower, however, working carefully, you can avoid the need to start work again if too much material is suddenly removed.

Markings / prints

Markings and fingerprints on the key blank arise due to the fact that the key blank made of metal is pressed against the holding devices in the cylinder (pins / discs), which are also made of metal.

Each time the metals come into contact with each other or rub and scratch their surfaces, a marking or imprint occurs.

For impression technology, this means that these markings or prints must be clearly recognizable in order to file in the right place. At the beginning of the impression process, labeling is difficult to determine, but at the end of the process they become larger, easier to identify and process.

Attention: If already at the beginning of the impression process at a certain site or at a completely certain depth, too much marking is obtained, then in most cases this indicates that the following factor takes place:

  1. In this section, we are actually talking about depth No. 1. In this case, the impression process for this pin in the cylinder is completed.
  2. Too much key material was removed during the preparation of the key blank. This is a big defect for impression technology, since even before the start of work, conditions are created for its termination.

Thus, an incorrectly prepared blank will each time have a marking on the appropriate place, while there is nothing to grind on it. This phenomenon is explained by the fact that the housing pin is already in the area of ​​the separation gap. If the movement is left or right, then the core pin is not blocked, but the body pin. Therefore, with each subsequent workflow, new markings or prints are made.

It is important to understand that markings created using impression technology can be very different from each other.

These differences depend on the following two factors:

  1. on the type of lock used with a cylinder, i.e. pin or disk holding devices (levers), etc.
  2. from the point at which markings are created during the workflow, that is, at the beginning, in the middle or at the end.

The type of marking is determined by the design of the holding devices of the unlocked lock. In principle, two different forms of marking are distinguished:

  • bar marking produced by lock disks with disk holding devices (levers).
  • spot marking produced by lock pins with pin holding devices.
Emergency Lock Release Guide

The closer you get to the final result of closures (cuts), the more distinct the markings become.

Emergency Lock Release Guide

The size and depth of individual markings varies from the very beginning to the end of the impression process.

The closer you get to the corresponding depth of the corresponding faults (cuts), the more distinct the markings become, while they should already be considered as final or final markings.

After processing the blanks with a file, the closing surface should be mirror smooth. Only in this case will it be possible to distinguish between initially weak markings.

File processing sites

When filed, the closing surface of the blank is prepared only in those places where, according to the measurement, there must be short circuits on the cylinder. Also, these areas should be mirror smooth.

File processing areas after measuring distances

Key blank preparation

There are four effective methods for preparing blanks:

  • File surface treatment
  • File processing sites
  • Edging
  • Blackening or staining contact planes

File surface treatment

This method makes it easy to file with a file the locking plane of the blank so that there is no chrome or paint on it so that after the first impression process (fingerprinting) it is possible to clearly distinguish the markings that appear and determine the distance between the individual closures.

Then, further processes of impression are carried out, as described previously.

Attention: When processing blanks with a file, remove less material than is required for the closure itself.

If you remove too much material, the consequence of this may be that the markings will not be accurate, and the work process will become impossible.


There are two methods described below for processing edging files:

  • Double-sided file processing of the locking surface of the blank at an angle of 45% each time, and this results in a edging similar to a knife blade. This means that from the flat surface of the disc, it is necessary to remove evenly under the bevel angles.
  • One-sided file processing of the locking surface of the blank at an angle of 45%. This means chamfering from the side face of the blank.

During both preparation options, care must be taken not to file too much material.

For locking cylinders with pins in the housing, it is also important that the edge of the blank passes under the center of the axis of the cylinder pins. Many key services willingly use these two options, since the sharp edging allows you to accurately determine the distance between the closures and, in addition, markings in more difficult cases with locks with restraints (levers) and a cross bolt.

You should try both options and choose a working option that provides you with the best result.

Blackening and staining of the contact surface of the disc

When blackening or staining the contact surface of the disc, we are talking about a method in which markings become noticeable in the opposite way. This means that after preliminary blackening or staining, the discs receive not a dark marking on a light background, but instead a light marking on a dark background.

In this case, there are also several training options.

1. Blacking soot

In this workflow, the corresponding blank is held above the lit lighter and directly above the flame. In this case, the disc is covered with soot and turns black. Marking is due to the fact that the discs or pins of the cylinder remove the soot layer, and in these places you can then see the clean metal of the disc, which is the marked point.


Here, the corresponding blank is also coated with a coloring liquid in the first working cycle. As a rule, this is paint from a felt-tip pen with a felt core or marking varnish when processing metal products. Labeling occurs as described when soot is used.

3.UV set

As with blackening with soot and dyeing, the blank is covered with a coloring liquid during the first working cycle, but in this case we are talking about a fluorescent liquid.

After taking markings or prints, keep the disc under an ultraviolet lamp. This special light provides clear visibility of markings and prints, as the corresponding spots become much darker than the other blocking area that glows under the UV lamp.

The methods described above are certainly not the only methods for pre-processing and preparing key blanks. They are only the most common and effective methods, and everyone can decide for himself what he will prefer. It is best if the user tries each method in different conditions and in different lighting conditions.

Work processes.

Step 1

The key blank is prepared for work according to the method of impression technique, namely:

  • File surface treatment
  • File processing sites
  • Edging
  • Blacking / staining

Step 2

The key blank is inserted as deep as possible into the locking channel of the cylinder.

Step 3

Turn the key disc with moderate effort to the right until it stops. Press up and down

Step 4

Press the key blank several times up and down. Then, with moderate pressure, turn the blank to the left. After this, push the blank a few more times up and down.

Step 5

Remove the key blank from the cylinder, and check the markings. At the location of the markings, the material is removed with a file, but only exactly where the markings are. Places without markings should not be processed, even if the distances between the faults are fixed.

The above steps 1 to 5 should be repeated for as long as a lock key is received.

Training, practical application and experience make the user this specialist method. Practice is especially important in order to be able to distinguish the necessary markings from insignificant ones.

For most users, it is the application of this technology that is on the verge of their visual abilities.

However, low vision is not an obstacle, as it can be compensated by modern polishing of magnifying glasses or working magnifiers, which, depending on the version, can be with or without backlight.

It should be recalled once again that the rotational movements to the stop should be performed with moderate effort, if only because with great effort it is impossible to obtain recognizable markings. There is only the danger that the key blank will be broken or bent.

Special care is required if there are disk restraints and cylinders with a transverse bolt. For these systems, too much force during rotation can damage the cylinder, since the washers or pins will be bent.

On the other hand, a little effort is not enough to block the pins. As a result, markings on the disc either do not appear at all or very vague prints appear.

In order to successfully use impression technology, the user must train for a long time in obtaining the correct effort during rotation.

Here are books that provide even more valuable knowledge in castles. Keybooks.

SA McLean, "The Impression System of Key Fitting", Dire Locksmith
Supply Co., 2201 Broadway, Denver, Colorado 808205, 1946 "Locksmithing and Keymaking Course Manual", Locksmithing Institute, Little Falls, New Jersey, 1968
"Padlock Handbook", Locksmith Ledger, 2720 Des Plaines Ave., DesPlaines, Ill., 60018, 1970
"How To Do It For Locksmiths", Locksmith Ledger, 1800 Oakton St., DesPlaines, Ill., 60018, 1971
"Know How for Locksmiths", Locksmith Ledger, 1970
"The Lock Pick Design Manual", Paladin Press, PO Box 1307, Boulder, Colorado 80302, circa 1975
TC Mickley, "Lock Servicing, Volume 4", Locksmith Ledger, 850 Busse Highway, Park Ridge, IL 60068, 1980
Eddie the Wire, "How to Make Your Own Professional Lock Tools, Volume2", Loompanics Unlimited, PO Box 1197, Port Townsend, WA 98368, 1981
Hank Spicer, "Impressioning with Hankman", RSG Publishing Corp., Dallas, Texas, 1995

The rest of the publication does not make sense, since it is already intended for professionals.

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